Very interesting and streamlined decklist. I might have to give this a shot a tourney sometime!
Just a couple questions. Why not run Mox Emerald for added help vs. spheres and another way to cast flashback on grudge? Does the deck just not have that kind of room? Turn 1 Thing seems like it could be good at times.
Also, how were the two pyroblasts? Did you feel like they came up often enough as a blowout card? I might consider some number of steel sabotage if shops was giving me problems. Just a thought.
Anyhoo, really nifty list. I will have to test it out real soon. Thanks man!